Electrostatic atomizing device and air conditioner using same

ABSTRACT

An electrostatic atomizing device includes an atomizing electrode which generates charged fine water particles negatively charged in the form of mist, by generating an electric field when a high negative voltage is applied thereto in a state in which water is supplied; a water supply portion which supplies the water to the atomizing electrode; a discharge detection portion which detects whether negative ion discharge, indicating discharge in which only negative ions are generated without generating the charged fine water particles, is occurring at the atomizing electrode or not; and a control portion which reduces the electric field intensity of the electric field generated by the atomizing electrode when the discharge detection portion detects the occurrence of the negative ion discharge.

TECHNICAL FIELD

This invention relates to an electrostatic atomizing device, and to an air conditioner using such an electrostatic atomizing device.

BACKGROUND ART

An electrostatic atomizing device causes Rayleigh splitting of water supplied to an atomizer electrode to cause atomization by applying a high voltage across the atomizer electrode (discharge electrode) and an opposing electrode and inducing discharge. As a result, charged fine water particles of nanometer size (nano-size mist) are obtained. Such an electrostatic atomizing device is for example installed in a dryer, as in Patent Document 1 by the present applicant, and has been favorably evaluated. Various applications for such electrostatic atomizing devices are being studied. In particular, the charged fine water particles contain OH radicals, and have a long lifetime. Further, a large quantity of charged fine water particles is dispersed into the air. Hence charged fine water particles adhere can effectively act on malodorous components adhering to wall surfaces, clothing, curtains, and similar to effectively act on malodorous components, and can deodorize.

For this reason, the use of electrostatic atomizing devices in air conditioners to perform deodorizing is being studied. An air conditioner comprising an electrostatic atomizing device is particularly well-suited to automotive uses, employed in confined spaces.

However, in such applications, there arises a problem which is not present in dryers. This problem is that negative ion discharge, in the initial state with no water droplets which is effective in a dryer, has no effect for the above-described deodorizing. Even though there is no deodorizing effect, the stage in which negative ion discharge is occurring may be handled as a transient stage from the time the dryer power is turned on until electrostatic atomizing discharge is begun. However, negative ion discharge imparts damage to the atomizing electrode, due to sputtering phenomena and similar. Consequently, in an air conditioner which is used for a much longer period of time than a dryer, damage to the atomizing electrode affects the equipment lifetime and so poses a problem. Further, there is also a desire to be able to rapidly start electrostatic atomizing discharge and obtain the deodorizing effect.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Patent Application Laid-open No. 2008-73291

SUMMARY OF INVENTION

This invention has as an object the provision of an electrostatic atomizing device capable of suppressing negative ion discharge, as well as an air conditioner using such a device.

In one mode of this invention, an electrostatic atomizing device comprises:

an atomizing electrode which generates charged fine water particles negatively charged in the form of mist, by generating an electric field when a high negative voltage is applied thereto in a state in which water is supplied;

a water supply portion which supplies the water to the atomizing electrode;

a discharge detection portion which detects whether negative ion discharge, indicating discharge in which only negative ions are generated without generating the charged fine water particles, is occurring at the atomizing electrode or not; and

a control portion which reduces the electric field intensity of the electric field generated by the atomizing electrode when the discharge detection portion detects the occurrence of the negative ion discharge.

Negative ion discharge is unnecessary in applications to air conditioners for the purpose of deodorization. And, negative ion discharge imparts damage to the atomizing electrode. In this configuration, when negative ion discharge is detected, negative ion discharge halting control is executed, by lowering the electric field intensity of the electric field generated by the atomizing electrode. Hence negative ion discharge is suppressed in air conditioners used over long periods of time, so that wear of the atomizing electrode is suppressed, and the equipment lifetime can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the electrical configuration of the electrostatic atomizing device in a first embodiment of the invention;

FIG. 2 is a flowchart used to explain operation of the electrostatic atomizing device in the first embodiment of the invention;

FIG. 3 is a graph showing the relation between the voltage value of the voltage applied to the atomizing electrode, and the current value of the discharge current occurring due to application of the applied voltage, to explain operation of the electrostatic atomizing device of the first embodiment of the invention;

FIG. 4 is a cross-sectional view showing schematically the structure of the atomizing electrode in an ion dryer;

FIG. 5 is a flowchart used to explain operation of the electrostatic atomizing device in a second embodiment of the invention;

FIG. 6 is a flowchart used to explain operation of the electrostatic atomizing device in a third embodiment of the invention;

FIG. 7 is a graph showing the relation between the voltage value of the voltage applied to the atomizing electrode, and the current value of the discharge current occurring due to application of the applied voltage, to explain operation of the electrostatic atomizing device in a fourth embodiment of the invention;

FIG. 8 is a flowchart used to explain operation of the electrostatic atomizing device in the fourth embodiment of the invention;

FIG. 9 is a graph showing the relation between the voltage value of the voltage applied to the atomizing electrode, and the current value of the discharge current occurring due to application of the applied voltage, to explain operation of the electrostatic atomizing device in a fifth embodiment of the invention;

FIG. 10 is a flowchart used to explain operation of the electrostatic atomizing device in the fifth embodiment of the invention;

FIG. 11 is a block diagram showing the electrical configuration of the electrostatic atomizing device in a sixth embodiment of the invention;

FIG. 12 is a block diagram showing the electrical configuration of the electrostatic atomizing device in a seventh embodiment of the invention; and

FIG. 13 is a cross-sectional view showing schematically an example of the configuration of the air conditioner in one embodiment e of the invention.

DESCRIPTION OF EMBODIMENTS

First, electrostatic atomizing devices of first to seventh embodiments of the invention are explained, together with drawings. And finally, an air conditioner of an embodiment of the invention is explained, together with drawings.

Electrostatic Atomizing Devices Embodiment 1

FIG. 1 is a block diagram showing the electrical configuration of the electrostatic atomizing device 1 in a first embodiment of the invention. This electrostatic atomizing device 1 comprises an atomizing block 2, high-voltage power supply circuit 3, Peltier power supply circuit 4, discharge current detection circuit 5, high-voltage power supply voltage detection circuit 6, and microcomputer (control portion) 7. This electrostatic atomizing device 1 is provided on the downstream side in the direction of flow of air from the filter 90 of an air conditioner 30 (see FIG. 13). For example, if the air conditioner is air cleaning equipment, charged fine water particles (nano-size mist) leaving the electrostatic atomizing device 1 by means of an ion wind generated from an ion generation portion (not shown) is carried on the air current of the air conditioner 30, and is dispersed within the room.

The atomizing block 2 comprises an atomizing electrode 13 having a spherical body 12 on the tip of a column 11; an opposing electrode 14 which opposes the atomizing electrode 13; and a Peltier element 15 which cools the base of the atomizing electrode 13. The Peltier power supply circuit 4 comprises a DC/DC converter 16. This DC/DC converter 16 supplies a power supply voltage for cooling to the Peltier element 15, and by this means the atomizing electrode 13 is cooled. At this time, surrounding water vapor adheres to the surface of the atomizing electrode 13, so that condensed water is obtained on the atomizing electrode 13. The Peltier power supply circuit 4 and Peltier element 15 form a water supply portion.

The microcomputer 7 provides cooling control signals to the Peltier power supply circuit 4, and by controlling the voltage value of the voltage applied to the Peltier power supply circuit 4, executes control such that a constant amount of water is obtained from the Peltier element 15, as explained below. The microcomputer 7 provides ON/OFF control signals and voltage adjustment signals to the high-voltage power supply circuit 3, and causes the high-voltage power supply circuit 3 to assume the ON state, as well as causing the high-voltage power supply circuit 3 to apply a high voltage at a prescribed voltage value (a high negative voltage; similarly below) to the atomizing electrode 13. At this time, electrostatic atomizing discharge is performed across the atomizing electrode 13 and the opposing electrode 14, and the charged fine water particles (nano-size mist) are generated.

Here, through electrostatic atomizing discharge, a discharge current flows from the atomizing electrode 13, via the opposing electrode 14, discharge current detection circuit 5, and high-voltage power supply circuit 3, to the atomizing electrode 13. This discharge current is detected by the discharge current detection circuit 5 which is electrically connected to the opposing electrode 14. Also, the discharge current detection circuit 5 detects the discharge current value of the detected discharge current as well.

The voltage value of the high voltage applied to the atomizing electrode 13 is detected by the high-voltage power supply voltage detection circuit 6 which is electrically connected to the high-voltage power supply circuit 3. And, the discharge current value of the discharge current detected by the discharge current detection circuit 5, and the voltage value of the high voltage detected by the high-voltage power supply voltage detection circuit 6, are fed back to the microcomputer 7. The microcomputer 7 reflects the fed-back discharge current value and voltage value in the control of the Peltier power supply circuit 4 and high-voltage power supply circuit 3, and executes control such that a constant amount of charged fine water particles (nano-size mist) is generated by the electrostatic atomizing discharge.

The discharge current detection circuit 5 detects the discharge current value of the discharge current flowing from the opposing electrode 14 to the discharge current detection circuit 5. This discharge current detection circuit 5 comprises, for example, a current-voltage conversion resistor provided in a state in series in the current path, and an amplifier or similar which amplifies the voltage obtained from the current-voltage conversion resistor. When an opposing electrode 14 is not provided, it is preferable that a discharge current detection circuit 5 a provided between the high-voltage power supply circuit 3 and the atomizing electrode 13 detects the discharge current flowing from the high-voltage power supply circuit 3 to the atomizing electrode 13.

In the electrostatic atomizing device 1 configured as described above, it should be noted that, in this embodiment, upon detection by the discharge current detection circuit 5 of the occurrence of the negative ion discharge not accompanied by electrostatic atomization, the microcomputer 7 causes the setting state of the voltage value of the voltage adjustment signal output to the high-voltage power supply circuit 3 to be changed, thereby lowering the absolute value of the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13. Hence the electric field intensity generated by the atomizing electrode 13 can be lowered, and negative ion discharge can be halted.

FIG. 2 is a flowchart used to explain control operation of the microcomputer 7. The microcomputer 7 causes the high-voltage power supply circuit 3 to start application of a high voltage to the atomizing electrode 13 (step S1). At this time, the Peltier power supply circuit 4 remains halted. Then, when a predetermined first time has elapsed after the start of the processing indicated in step S1, the microcomputer 7 advances to the processing of step S3. It is desirable that this first time comprise at least the time for the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13 to rise from the initial 0 V to reach a prescribed target voltage. Further, it is preferable that the first time be a time such that the high voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13 can assume a stable state. Also, it is preferable that the first time be selected to be sufficiently long that any moisture adhering to the atomizing electrode 13 is evaporated. From the above conditions, it is preferable that the first time be between 5 seconds and 30 seconds approximately.

In step S3, the microcomputer 7 judges whether the discharge current value detected by the discharge current detection circuit 5 is equal to or greater than a predetermined threshold value is not. That is, in step S3, if the discharge current value of the discharge current is equal to or greater than the threshold value (YES in step S3), the microcomputer 7 judges that discharge is occurring across the atomizing electrode 13 and opposing electrode 14. Here, as explained above, the Peltier power supply circuit 4 remains halted. Hence water is not being supplied to the atomizing electrode 13, so that the discharge across the atomizing electrode 13 and opposing electrode 14 is negative ion discharge. Hence until negative discharge is no longer detected by the discharge current detection circuit 5, the microcomputer 7 repeats processing to reduce the absolute value of the voltage value of the high voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode (step S4) and processing to judge whether the discharge current value of the discharge current detected by the discharge current detection circuit 5 is equal to or greater than the threshold value or not (step S5).

That is, as shown in FIG. 3, after executing control to prevent negative ion discharge to repeatedly decrease the absolute value of the voltage applied to the atomizing electrode 13 until a discharge current with discharge current value equal to or greater than the threshold value is no longer detected, the microcomputer 7 proceeds to the electrostatic atomizing control of step S6. Here, in FIG. 3 the discharge current value used as the threshold value is 0 μA. Also, “electrostatic atomizing control” means control in which, by at least causing supplying water and application of a high voltage to the atomizing electrode 13 and causing generation of electrostatic atomizing discharge, the computer 7 executes control to cause generation of charged fine water particles at the atomizing electrode 13.

Further, when in the judgment of step S3 the discharge current value is less than the threshold value (NO in step S3), the microcomputer 7 directly proceeds to the processing of step S6. Here, the microcomputer 7 and discharge current detection circuit 5 form the discharge detection portion.

In electrostatic atomizing control, the Peltier power supply circuit 4 is operated so as to supply a constant amount of water to the atomizing electrode 13, as explained above. Here, the resistance value of the water generated by condensation of moisture in the air is small. Consequently if the voltage value of the high voltage applied to the atomizing electrode 13 is constant at for example −5 kV, then the greater the amount of water supplied to the atomizing electrode 13 by condensation of moisture in the air due to the Peltier element 15, the greater is the discharge current flowing from the atomizing electrode 13 to the opposing electrode 14 (the discharge current value detected by the discharge current detection circuit 5). Hence if a cooling control signal is output to the Peltier power supply circuit 4 such that the discharge current value represented by the discharge current signal is constant, then a constant amount of water is supplied to the atomizing electrode 13.

Through this configuration, upon detection of the negative ion discharge by the discharge current detection circuit 5, which is unnecessary in uses for the purpose of deodorizing and which imparts damage to the atomizing electrode 13, the microcomputer 7 executes control to halt the negative ion discharge, so that wear of the atomizing electrode 13 in an air conditioner used over a long period of time is suppressed, and the equipment lifetime is extended. Further, during the period until the first time has elapsed, the microcomputer 7 lowers the voltage value of the high voltage applied to the atomizing electrode 13 until a voltage value is reached at which negative ion discharge does not occur. Hence when the first time has elapsed, the voltage value of the high voltage applied to the atomizing electrode 13 is a value such that negative ion discharge does not occur, so that electrostatic atomizing discharge can be started rapidly, and a deodorizing effect can be obtained.

Here, it is easy to perform control so as to transition to electrostatic atomizing discharge after performing negative ion discharge for a time by supplying water, as in the above-described dryer. However, if mainly electrostatic atomizing discharge is performed without performing negative ion discharge, as in the present embodiment, it is not sufficient to simply cause discharge after waiting until an adequate amount of water has been supplied. Hence for the reason described below, it is difficult to apply such dryer control to control of the electrostatic atomizing device 1.

Specifically, as shown in FIG. 4, the atomizing electrode of the dryer is configured with a sharp protrusion 102 formed on a spherical body 101. And, an electric field is concentrated between the protrusion 102 and the opposing electrode 103 to start the negative ion discharge. When water is supplied to the protrusion 102 and the protrusion 102 is covered with water (Taylor cone 104), there is switching to electrostatic atomizing discharge.

At this time, the more the water increases at the atomizing electrode (the longer the Taylor cone 104), the lower is the resistance value between the atomizing electrode comprising the spherical body 101 and the opposing electrode 103, so that electrostatic atomizing discharge is performed at a low voltage value. Further, the longer the Taylor cone 104 at the atomizing electrode, the lower is the resistance value between the atomizing electrode and the opposing electrode 103, so that a discharge current with a large discharge current value occurs at a low voltage value. Thus it is seen that there is a proportional relationship between the amount of water at the atomizing electrode and the discharge current value.

So long as a high voltage with a constant voltage value is being applied to the atomizing electrode, the amount of water increases at the atomizing electrode (the Taylor cone 104 lengthens), and to this extent the resistance value between the atomizing electrode comprising the spherical body 101 and the opposing electrode 103 declines, so that the discharge current value increases. In general, the quantity of charged fine water particles (nano-size mist) is affected by the discharge current value. Also, the quantity of water at the atomizing electrode and the discharge current value are in a proportionality relationship, as explained above. Hence it is seen that in order to adjust the quantity of charged fine water particles, the quantity of water at the atomizing electrode may be adjusted.

However, in an electrostatic atomizing device 1 which is to be made to primarily perform electrostatic atomizing discharge, the atomizing electrode 13 is formed using only a spherical body 12, as shown in FIG. 1. The spherical body 12 does not comprise a protrusion 102, as in the case of the spherical body 101 of the dryer. Hence if a discharge current flows when a high voltage is applied to the atomizing electrode 13 with a voltage value smaller than the voltage value which initiates a discharge current (a specified application voltage), the cause of the discharge current is not known.

That is, the spherical body 12 of the atomizing electrode does not comprise a protrusion 102, and so the microcomputer 7 cannot judge whether a discharge current has flowed due to the occurrence of a Taylor cone of constant length in electrostatic atomizing discharge, or whether a discharge current has flowed due to the occurrence of the negative ion discharge due to foreign matter adhering, with a protruding shape, to the atomizing electrode 13. Hence the microcomputer 7 cannot ascertain whether the currently occurring discharge is micro-ion discharge or is electrostatic atomizing discharge.

In general, in micro-ion discharge only negative ions are generated, and charged fine water particles are not generated. Hence in a state in which the microcomputer 7 cannot ascertain whether the discharge currently occurring is micro-ion discharge or electrostatic atomizing discharge, of course the quantity of charged fine water particles cannot be adjusted by merely adjusting the discharge current value. Hence it is difficult to employ a discharge current value control method such as is used in dryers to an electrostatic atomizing device employed to primarily cause electrostatic atomizing discharge.

Hence in this embodiment, the microcomputer 7 causes the Peltier power supply circuit 4 to halt the supply of water for a first time from the time at which application of the high voltage to the atomizing electrode 13 by the high-voltage power supply circuit 3 is started. Hence even when moisture adheres to the atomizing electrode 13 before the start of use in a high-temperature and high-humidity environment, or even when the time elapsed from the end of the time the equipment was previously used is short, so that moisture from the time of previous use remains on the atomizing electrode 13, this moisture is evaporated within this first time. Hence a state results in which no moisture adheres to the atomizing electrode 13. Here, even when foreign matter adheres to the spherical body 12 in the shape of a protrusion 102, this is removed from the atomizing electrode 13 by the ion wind due to negative ion discharge at the atomizing electrode 13 by the time the first time has elapsed.

Then, in a state in which neither water nor foreign matter adhere to the atomizing electrode 13, the microcomputer 7 causes the discharge current detection circuit 5 to detect whether negative ion discharge is occurring or not. To this end, in a state in which there is the possibility of the occurrence of electrostatic atomizing discharge, the microcomputer 7 can suspend operation to detect whether discharge is negative ion discharge or not, and can reliably detect negative ion discharge.

That is, in a state in water remains on the atomizing electrode 13, and it cannot be ascertained whether a discharge current is occurring due to negative ion discharge, or whether a discharge current is occurring due to electrostatic atomizing discharge, the microcomputer 7 does not detect whether negative ion discharge is occurring or not. When a state occurs in which moisture does not adhere to the atomizing electrode 13 (in the state in which the first time has elapsed), the microcomputer 7 performs detection of whether negative ion discharge is occurring or not.

After detection of the occurrence of the negative ion discharge, upon detection of a discharge current when a high voltage, with voltage level lowered such that negative ion discharge does not occur, is applied to the atomizing electrode 13, the microcomputer 7 detects the occurrence of electrostatic atomizing discharge, rather than micro-ion discharge.

Further, the controller 7 performs feedback control, based on the discharge current value of the discharge current detected when a high voltage, lowered to a voltage value at which negative ion discharge does not occur, is applied to the atomizing electrode 13. For example, the microcomputer 7 control the Peltier power supply circuit 4 such that an amount of water corresponding to the discharge current value is supplied to the atomizing electrode 13 by the Peltier element 15, in “a relation of proportionality of the amount of water at the atomizing electrode 13 and the discharge current value” (described above).

Further, as the water supply portion, a heat exchanger employing the Peltier element 15 is used. In general, start-up and shut-down of a Peltier element 15 are fast. For example, in 5 seconds a Peltier element 15 can cause condensed water to adhere to the atomizing electrode 13. Hence satisfactory response characteristics for starting and halting supply of water to the atomizing electrode 13 can be obtained.

Embodiment 2

FIG. 5 is a flowchart used to explain operation of the electrostatic atomizing device 1 in a second embodiment of the invention. The configuration of the electrostatic atomizing device 1 shown in FIG. 1 can be used in the electrostatic atomizing device 1 of this embodiment. In the electrostatic atomizing device 1 of this embodiment, operation of the microcomputer 7 differs between in FIG. 2 and in FIG. 5. In FIG. 5, which is similar to FIG. 2, the same step numbers are assigned to corresponding processing, and explanations thereof are omitted. It should be noted that in this embodiment, after halting supply of water and waiting for a first time in step S2, upon detecting a discharge current value of the discharge current equal to or greater than a threshold value in step S3, no judgment of negative ion discharge is performed immediately, and processing returns to step S3 until a predetermined second time elapses, and after the second time has elapsed, judgment of negative ion discharge is performed. Here, the second time represents a time elapsed from the time of judgment in step S3 that the discharge current value is equal to or greater than the threshold value.

In this configuration, whether negative ion discharge is occurring or not is again judged after a second time from the previous judgment, for example, after one minute has elapsed. As a result, the following advantageous results are obtained from the second embodiment. That is, by shorting the first time to, for example, the abovementioned 5 seconds, erroneous judgments may occur in a state in which moisture adheres to the atomizing electrode 13. However, in the second embodiment, the moisture evaporates during the period from the erroneous judgment until the second time has elapsed. As a result, accurate judgment is performed the second time. Hence the time for initially judging whether a negative ion discharge is occurring or not can be set comparatively short, and therefore electrostatic atomizing discharge can be performed rapidly.

In the second embodiment, when negative ion discharge is continued even after the first and second times have elapsed (YES in step S11), the voltage value of the voltage applied to the atomizing electrode 13 is reduced in steps until a negative ion discharge is no longer detected (steps S4 and S5).

Embodiment 3

FIG. 6 is a flowchart used to explain operation of the electrostatic atomizing device 1 in a third embodiment of the invention. The configuration of the electrostatic atomizing device 1 shown in FIG. 1 can be used in the electrostatic atomizing device 1 of this embodiment. In the electrostatic atomizing device 1 of this embodiment, operation of the microcomputer 7 differs from that in FIG. 2 above and in FIG. 6. It should be noted that in this embodiment, the negative ion discharge detection processing indicated in steps S2 and S3 of FIG. 2 is performed in step S23.

That is, in the state in which the supply of water to the atomizing electrode 13 is halted during the period of the first time (step S2 in FIG. 2), the microcomputer 7 performs processing to judge whether the discharge current value is equal to or exceeds the threshold value (step S3 in FIG. 2). And, in step S3 in FIG. 2, upon detection of negative ion discharge (YES in step S3 of FIG. 2), the microcomputer 7 decreases in steps the voltage value of the high voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13.

Specifically, when in step S23 negative ion discharge is detected, the microcomputer 7 judges the discharge current value represented by the discharge current signal output from the discharge current detection circuit 5 (step S24). And, in step S41 the microcomputer 7 compares the discharge current value with a predetermined threshold value A, and when the discharge current value is less than the threshold value A, in step S42 sets the voltage applied to the atomizing electrode to a value smaller by a comparatively small voltage reduction amount Δ1. When on the other hand the discharge current value is equal to or greater than the threshold value A, in step S43 the voltage applied to the atomizing electrode 13 is set to a value smaller by a comparatively large voltage reduction amount Δ2.

After the processing represented by these steps S42 and S43, the microcomputer 7 judges whether negative ion discharge is continuing or not (step S5), and if it is judged that negative ion discharge is continuing (YES in step S5), the microcomputer 7 executes the processing of step S24. On the other hand, upon judging that negative ion discharge is not continuing, the microcomputer 7 performs the electrostatic atomizing control indicated by step S6.

Here, during negative ion discharge, the higher the voltage value of the high voltage applied to the atomizing electrode 13, the greater the increase in the quantity of electrons emitted from the atomizing electrode 13, so that the discharge current value is increased. Hence by setting a plurality of voltage reduction amounts Δ1, Δ2 as the amounts of reduction in the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13, and by using a larger reduction (Δ2) in the voltage value when the discharge current value is large, according to the discharge current value when negative ion discharge is occurring, and using a smaller reduction (Δ1) in the voltage value when the discharge current value is small, negative ion discharge can be rapidly stopped. Also, after stopping negative ion discharge, so long as there is no occurrence of the negative ion discharge, by applying a borderline voltage so that negative ion discharge does not occur, electrostatic atomizing can be induced with stability.

Embodiment 4

FIG. 7 is a waveform diagram used to explain operation of the electrostatic atomizing device 1 in a fourth embodiment of the invention. The configuration of the electrostatic atomizing device 1 shown in FIG. 1 can be used in the electrostatic atomizing device 1 of this embodiment as well. In the electrostatic atomizing device 1 of this embodiment, operation of the microcomputer 7 differs from the operation of the microcomputer 7 in the first embodiment. It should be noted that in this embodiment, the microcomputer 7 repeatedly lowers the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13. And, prior to lowering the applied voltage, the microcomputer 7 always first turns the high-voltage power supply circuit 3 OFF, using an ON/OFF control signal. Also, after first turning OFF the high-voltage power supply circuit 3 and lowering the applied voltage, the microcomputer 7 always puts the high-voltage power supply circuit 3 into the ON state, using an ON/OFF control signal.

FIG. 8 is a flowchart used to explain the operation. In step S23, the microcomputer 7 judges whether negative ion discharge is occurring or not. At this time, if negative ion discharge is occurring, the microcomputer 7 first turns OFF the high-voltage power supply circuit 3 in step S44.

Then, together with control to lower the applied voltage in step S45, the high-voltage power supply circuit 3 is turned ON. That is, the microcomputer 7 turns ON the power supply of the high-voltage power supply circuit 3 using an ON/OFF control signal. And, the microcomputer 7 reduces the voltage value of the high voltage applied by the high-voltage power supply circuit 3 by means of a voltage adjustment signal (step S45). Then, if negative ion discharge is not eliminated through voltage reduction control (YES in step S5), processing by the microcomputer 7 returns from step S5 to step S44, and voltage reduction control is repeated by the microcomputer 7 until negative ion discharge is eliminated.

When reducing the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13 in this way, by turning OFF the high-voltage power supply circuit 3, the microcomputer 7 forcibly cancels the state of negative ion discharge. Hence the microcomputer 7 causes negative ion discharge to be discontinued, and so damage to the atomizing electrode 13 can be suppressed.

Further, by reducing in steps the voltage applied to the atomizing electrode 13, the microcomputer 7 reduces the voltage value of the applied voltage to a voltage value at which negative ion discharge does not occur. Hence the microcomputer 7 can cause the high-voltage power supply circuit 3 to apply a high voltage to induce electrostatic atomizing discharge with stability, without causing negative ion discharge. In this fourth embodiment, when detected negative ion discharge has been eliminated (NO in step S5), electrostatic atomizing control is performed (step S6).

Embodiment 5

FIG. 9 is a waveform diagram used to explain operation of the electrostatic atomizing device 1 in a fifth embodiment of the invention. The configuration of the electrostatic atomizing device 1 shown in FIG. 1 can be used in the electrostatic atomizing device 1 of this embodiment as well. In the electrostatic atomizing device 1 of this embodiment, operation of the microcomputer 7 differs from the operation of the microcomputer 7 in the first embodiment described above. This embodiment is similar to the embodiment shown in FIG. 7 and FIG. 8 above. It should be noted that in this embodiment, when reducing the voltage applied by the high-voltage power supply circuit 3 to the atomizing electrode 13, the microcomputer 7 first turns OFF the high-voltage power supply circuit 3, and after negative ion discharge is no longer detected, and after further lowering by one step the applied voltage, proceeds to electrostatic atomizing control. In the example of FIG. 9, the discharge voltage value of the discharge current falls below the threshold value by lowering the voltage value in three steps, set in advance in the electrostatic atomizing device 1. However, the microcomputer 7 thereafter further lowers the voltage one step. As a result, a discharge current no longer flows.

Here, as one example of a voltage value lowered one more step in this embodiment, a voltage value “b” is shown which is in the range from 2 to 5% of the voltage value “a” in the voltage application cycle CY1 immediately before the relevant voltage application cycle CY2. That is, in the relevant voltage application cycle CY2, the high voltage “a”-“b” of the voltage value is applied to the atomizing electrode 13. At this time, a discharge current is no longer detected by the discharge current detection circuit 5.

FIG. 10 is a flowchart used to explain the operation. In steps S44 and S45 and in step S5, the microcomputer 7 lowers in steps the applied voltage. As a result, negative ion discharge is no longer detected. However, in this embodiment, after negative ion discharge is no longer detected, in step S46 once again the high-voltage power supply circuit 3 is turned OFF similarly to step S44, and in step S47 the applied voltage is lowered one step similarly to step S45. Here, in step S47 the microcomputer 7 turns ON the power supply of the high-voltage power supply circuit 3. And, by means of a voltage adjustment signal, the microcomputer 7 further reduces the voltage value of the high voltage applied by the high-voltage power supply circuit 3. And, in step S6 the microcomputer 7 performs electrostatic atomizing control.

In general, after negative ion discharge has been eliminated the applied voltage is in an unstable state. However, in this embodiment the microcomputer 7 can reliably halt negative ion discharge by lowering the voltage to a predetermined level below the voltage value at which negative ion discharge no longer occurs, such as for example to from 2 to 5% below the voltage value at which negative ion discharge no longer occurs, and consequently stable electrostatic atomizing can be performed.

Embodiment 6

FIG. 11 is a block diagram showing the electrical configuration of the electrostatic atomizing device 1 a in a sixth embodiment of the invention. The electrostatic atomizing device 1 a is similar to the electrostatic atomizing device 1 shown in FIG. 1 above. It should be noted that in this electrostatic atomizing device 1 a, a register 7 b, which is a storage portion, is provided in the microcomputer 7 a, and that a detection result (voltage value of the high voltage) of the high-voltage power supply voltage detection circuit 6 is stored as the default value in this register 7 b at the time that an negative ion discharge is no longer detected. The voltage value stored as a default value is set in the high-voltage power supply circuit 3 as the voltage value of the high voltage to be applied at the time of the next startup.

In this way, at the time of the next startup, the voltage value of the high voltage at which the negative ion discharge was no longer detected at the time of previous operation is used, so that the time for adjustment to the optimum applied voltage enabling prevention of negative ion discharge is shortened, and consequently electrostatic atomizing can be started rapidly.

Embodiment 7

FIG. 12 is a block diagram showing the electrical configuration of the electrostatic atomizing device 21 in a seventh embodiment of the invention. This electrostatic atomizing device 21 is similar to the electrostatic atomizing device 1 shown in FIG. 1 above; corresponding portions are assigned the same reference symbols, and explanations thereof are omitted. It should be noted that in this electrostatic atomizing device 21, a displacement device 22 is provided on the opposing electrode 14 which can change the distance between the atomizing electrode 13 and the opposing electrode 14, as indicated by the arrows 29. Upon detection of negative ion discharge, the microcomputer 27 causes the opposing electrode 14 to be moved in the axial direction of the atomizing electrode 13 and so to be moved away from the atomizing electrode 13. As a result, the electric field intensity in the region between the atomizing electrode 13 and the opposing electrode 14 is reduced.

This displacement device 22 comprises a support member 23 which supports the opposing electrode 14; a rack member 24, on which the support member 23 is mounted; a guide portion (not shown) which guides the rack member 24; a pinion gear 25 which meshes with the rack member 24; and a motor 26 which drives the pinion gear 25. The motor 26 is driven by a driving circuit 28. The driving circuit 28 operates according to distance control signals from the microcomputer 27. By means of this configuration also, negative ion discharge can be prevented.

Air Conditioner

FIG. 13 is a cross-sectional view showing schematically an example of the configuration of the air conditioner in one embodiment of the invention. In FIG. 13, a heating/cooling type air conditioner 30 is shown as an example.

In this air conditioner 30, an air suction opening 81 is provided in the upper portion of the front face of the housing 82. Air suctioned by the air suction opening 81 is passed through a filter 90 to remove dust and similar, and flows into the housing 82. In the figure, the arrows indicate the direction of flow of air within the housing 82 (hereafter called the direction D).

Air which has flowed into the housing 82 undergoes heat exchange by a heat exchanger (air conditioning portion) 80, and as a result warmed air or cooled air is generated. On the downstream side in the direction D of the heat exchanger 80 are provided two among the electrostatic atomizing devices 1, 1 a, and 21.

The charged fine water particles M1 generated by any among the electrostatic atomizing devices 1, 1 a, 21 are carried on the flow of air which has undergone heat exchange by the heat exchanger 80, and travels toward the air blow-out opening 87. Here, the flow of air which has undergone heat exchange is formed by rotation of a fan 83. The air blow-out opening 87 is provided with a louver 88. Hence charged fine water particles M1 traveling toward the air blow-out opening 87 are blown in the direction toward the louver 88. Here, the direction of orientation of the louver 88 is determined by rotation of a motor 100.

Further, within the housing 82 is provided a wall 84 to form an airflow path 85 from the air suction opening 81, through the fan 83, to the air blow-out opening 87. Here, the lower-rear portion in the housing 82 is partitioned from the airflow path 85 by the wall 84, and is a dead space used to draw out an exhaust drain pipe 89 from the right edge or left edge of the housing 82 to the outside. Any one among the above-described electrostatic atomizing devices 1, 1 a, 21 is provided in the dead space. To any one among the electrostatic atomizing devices 1, 1 a, 21 a delivery tube 86, to deliver charged fine water particles M2 occurring in one among the electrostatic atomizing devices 1, 1 a, 21 from the dead space to the interior of the housing 82, is connected.

Hence the charged fine water particles M2 occurring in one among the electrostatic atomizing devices 1, 1 a, 21 is delivered to the interior of the housing 82, and consequently the charged fine water particles M2 are carried on the flow of air in the housing 82, and travel toward the air blow-out opening 87. Hence the charged fine water particles M2 are blown in the direction of the orientation of the louver 88 in the air blow-out opening 87.

Any one among the microcomputers 7, 7 a, 21 not only controls any one among the electrostatic atomizing devices 1, 1 a, 21, but also executes overall control of the air conditioner 30. In the figure, the dot-dash arrows represent control signals output from the microcomputer 7, 7 a, or 21.

The above-described specific embodiments mainly comprise inventions having the following configurations.

The electrostatic atomizing device of a first mode of the invention comprises:

an atomizing electrode which generates charged fine water particles negatively charged in the form of mist, by generating an electric field when a high negative voltage is applied thereto in a state in which water is supplied;

a water supply portion which supplies the water to the atomizing electrode;

a discharge detection portion which detects whether negative ion discharge is occurring at the atomizing electrode or not, representing discharge which generates only negative ions without generating charged fine water particles; and

a control portion which, when the occurrence of the negative ion discharge is detected by the discharge detection portion, reduces the electric field intensity of the electric field generated by the atomizing electrode.

In this configuration, in the preliminary stage of electrostatic atomizing discharge in which discharge occurs between a Taylor cone of water drops adhering to the atomizing electrode and an opposing pole (an opposing electrode, a housing or similar at GND potential accommodating the electrostatic atomizing device, or another member having polarity opposite that of the atomizing electrode), when the occurrence of the negative ion discharge, in which direct discharge occurs between the atomizing electrode and the opposing pole without being accompanied by electrostatic atomizing, is detected by the discharge detection portion, the control portion controls the high-voltage power supply circuit to cause reduction of the voltage applied to the atomizing electrode, or else withdraws the opposing pole from the atomizing electrode, and so lowers the electric field intensity generated by the atomizing electrode.

Hence when negative ion discharge, which is unnecessary when used for deodorizing purposes and imparts damage to the atomizing electrode, is detected by the discharge detection portion, the control portion executes control to halt the negative ion discharge, so that wear of the atomizing electrode is suppressed in an air conditioner used for extended lengths of time, and the equipment lifetime is extended.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, that the control portion be configured to cause the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, that the control portion halt the supply of the water to the atomizing electrode by the water supply portion during the period from when the high-voltage power supply circuit is caused to apply the high negative voltage to the atomizing electrode until a predetermined first time has elapsed, and that, when the first time has elapsed after causing the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, the control portion cause the discharge detection portion to detect whether negative ion discharge is occurring or not.

In this configuration, the control portion controls the timing of the start of application of a high voltage by the high-voltage power supply circuit and controls the supply of water by the water supply portion, and in addition controls the timing of detection by the discharge detection portion. And, the control portion halts the supply of water by the water supply portion for a predetermined first time from the start of application of the high voltage. Hence even when moisture adheres to the atomizing electrode prior to the start of use in a high-temperature, high-humidity environment, or when the time elapsed from the end of the previous use is short and moisture from the previous use remains on the atomizing electrode, this moisture evaporates during the first time. Thereafter, the control portion causes the discharge detection portion to judge whether negative ion discharge is occurring or not.

Hence in circumstances in which there is the possibility of occurrence of electrostatic atomizing discharge, operation to detect whether discharge is negative ion discharge is occurring or not is stopped, and negative ion discharge can be reliably detected. The first time is the time sufficient for evaporation even when moisture adheres to the atomizing electrode as described above, and is approximately 5 to 30 seconds.

In the above configuration, it is desirable that, when the occurrence of the negative ion discharge is detected by the discharge detection portion, the control portion further cause the discharge detection portion to detect whether negative ion discharge is occurring or not during the period from the detection of the occurrence of the negative ion discharge until a predetermined second time has elapsed, and when the occurrence of the negative ion discharge is detected by the discharge detection portion during the period from the time of detection of the occurrence of the negative ion discharge until the second time has elapsed, the control portion reduce the electric field intensity of the electric field generated by the atomizing electrode.

By means of this configuration, whether negative ion discharge is occurrence is again judged after a second time, such as for example 1 minute, has elapsed from the previous judgment, and so even if the first time is shortened to for example approximately 5 seconds as described above, and erroneous judgement of the state of adhesion of moisture to the atomizing electrode is made, the moisture evaporates during the period in which the second time elapses, so that accurate judgment can be performed.

Hence the first time until the initial judgment that there is no negative ion discharge can be set to be comparatively short, and switching to electrostatic atomizing discharge can be performed rapidly.

In the above configuration, it is desirable that the water supply portion be a Peltier element provided at the base of the atomizing electrode.

In this configuration, water adhering to the atomizing electrode, by cooling of the atomizing electrode by the Peltier element, is used for atomizing. Hence startup of the Peltier element can be performed rapidly, condensed water can be made to adhere to the atomizing electrode in for example 5 seconds, and satisfactory response for water supply startup and halting can be obtained.

In the above configuration, it is desirable that the second time be 1 minute.

In this configuration, the presence or absence of negative ion discharge can be accurately judged during the period from an erroneous judgement of negative ion discharge until 1 minute has elapsed. Hence there is little tendency for damage to be imparted to the atomizing electrode due to sputtering phenomena or similar.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be comprised, and that the control portion reduces the electric field intensity of the electric field generated by the atomizing electrode by reducing a voltage value of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit.

In general, when the voltage value of the high negative voltage applied to the atomizing electrode is reduced, the electric field intensity of the electric field generated by the atomizing electrode declines. And when the electric field intensity of the electric field declines, the discharge current flowing due to negative ion discharge decreases. And when the discharge current decreases, there is a tendency for the negative ion discharge to be eliminated.

Hence in this configuration, by reducing the voltage value of the high negative voltage applied to the atomizing electrode and lowering the electric field intensity of the electric field generated by the atomizing electrode, the discharge current due to negative ion discharge is decreased. Hence negative ions can be eliminated through simple control in which the voltage value of the high negative voltage applied to the atomizing electrode is reduced.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, that a plurality of voltage values be set in advance as voltage values for the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, that the discharge detection portion be configured to further detect the discharge current value of the discharge current representing the current occurring due to negative ion discharge, and that the control portion reduce in steps the voltage value of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, according to the discharge current value detected by the discharge detection portion.

In this configuration, the voltage value of the high negative voltage applied to the atomizing electrode is reduced in steps until the negative ion discharge is eliminated. Hence after the negative ion discharge is eliminated, a borderline voltage so that negative ion discharge does not occur can be applied to the atomizing electrode, to induce electrostatic atomizing. Hence electricity fees can be suppressed.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, and that the control portion turn OFF and then turn ON the high-voltage power supply circuit as well as reduces the voltage value of the high negative voltage applied to the atomizing electrode.

By means of this configuration, the state of negative ion discharge can be forcibly eliminated, and damage to the atomizing electrode can be suppressed without continuation of negative ion discharge; in addition, a high voltage can be applied so as to stably induce electrostatic atomizing discharge, without causing negative ion discharge.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, that a plurality of voltage values be set in advance as voltage values for the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, that the discharge detection portion be configured to further detect the discharge current value of the discharge current representing the current occurring due to negative ion discharge, and that the control portion repeatedly turn OFF and then turn ON the high-voltage power supply circuit as well as reduce in steps the voltage value of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, until the occurrence of the negative ion discharge is no longer detected by the discharge detection portion.

By means of this configuration, in a state in which negative ion discharge has been interrupted, the voltage value of the high negative voltage applied to the atomizing electrode is set to a voltage value at which negative ion discharge does not occur. Hence damage to the atomizing electrode due to sputtering phenomena and similar can be suppressed. Further, the voltage value of the high negative voltage applied to the atomizing electrode is reduced in steps until the negative ion discharge is eliminated. Hence after elimination of the negative ion discharge, a high voltage at a borderline voltage value at which negative ion discharge does not occur can be applied to the atomizing electrode to cause electrostatic atomizing. Hence electricity fees can be suppressed.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, and that the control portion reduce the voltage value of the high negative voltage applied to the atomizing electrode, and to this end, when the discharge detection portion no longer detects the occurrence of the negative ion discharge, further reduces the voltage value of the high negative voltage.

In general, the application voltage is in an unstable state after elimination of the negative ion discharge. Hence by means of this configuration, by further reducing the voltage value to a level determined in advance, for example 2 to 5% below the voltage value at the time of elimination of the negative ion discharge, stable electrostatic atomizing can be performed.

In the above configuration, it is desirable that a storage portion which stores the voltage value of the high negative voltage obtained when the discharge detection portion no longer detects the negative ion discharge be comprised, that the control portion cause the storage portion to store the voltage value of the high negative voltage obtained when the discharge detection portion no longer detects the negative ion discharge, and set the voltage value stored in the storage portion as a default voltage value.

By means of this configuration, the voltage value stored as the default value is set in the high-voltage power supply circuit as the voltage value of the high voltage to be applied at the time of the next startup. Hence at the time of the next startup the voltage value of the high voltage at which negative ion discharge was no longer detected during the preceding operation is used, so that the time for adjustment to the optimum applied voltage at which negative ion discharge can be prevented is shortened, and consequently electrostatic atomizing can be started rapidly.

In the above configuration, it is desirable that a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode be further comprised, that the discharge detection portion be configured to further detect the discharge current value of a discharge current representing the current occurring due to negative ion discharge, and that, when a first time has elapsed after causing the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, when the discharge detection portion detects the occurrence of the negative ion discharge, the control portion judges the discharge current value detected by the discharge detection portion, and during the period between the time when the discharge current value is less than a predetermined threshold value and the time when the discharge current value is equal to or greater than a predetermined threshold value, employs different voltage value magnitudes for application to the atomizing electrode as the high negative voltage.

In this configuration, the amount of reduction of the voltage value of the high negative voltage applied to the atomizing electrode differs according to the discharge current value during negative ion discharge. Hence when for example the discharge current value is large the amount of reduction of the voltage value is made large, and when the discharge current value is small the amount of reduction of the voltage value is made small, so that the state of occurrence of the negative ion discharge can be ended efficiently.

In the above configuration, it is desirable that the voltage value applied as the high negative voltage when the discharge current value is equal to or greater than a predetermined threshold value be made greater than the voltage value applied as the high voltage when the discharge current value is less than the threshold value.

In this configuration, when the discharge current value during negative ion discharge is large, the amount of reduction of the voltage value is large, and when the discharge current value is small the amount of reduction of the voltage value is small, so that the state of occurrence of the negative ion discharge can be ended rapidly.

In the above configuration, it is desirable that an opposing electrode, provided in opposition to the atomizing electrode, be further comprised, and that by causing the atomizing electrode and the opposing electrode to be moved apart, the control portion reduces the electric field intensity of the electric field generated from the atomizing electrode toward the opposing electrode.

In this configuration, negative ion discharge is easily prevented without requiring processing such as reduction of the voltage value of the high negative voltage applied to the atomizing electrode.

In the above configuration, it is desirable that the first time be a time in the range from 5 seconds to 30 seconds.

In this configuration, even if moisture adheres to the atomizing electrode, the occurrence of the negative ion discharge is detected after sufficient time for the moisture to evaporate has elapsed. Hence the occurrence of the negative ion discharge can be accurately detected.

Further, the air conditioner of another mode of the invention comprises:

the electrostatic atomizing device according to the first mode; and

an air conditioning portion which performs air conditioning.

In this configuration, the electrostatic atomizing device according to the first mode is comprised. Hence an air conditioner from which the advantageous results of the first mode are obtained is provided. 

1-16. (canceled)
 17. An electrostatic atomizing device, comprising: an atomizing electrode which generates charged fine water particles negatively charged in the form of mist, by generating an electric field when a high negative voltage is applied thereto in a state in which water is supplied; a water supply portion which supplies the water to the atomizing electrode; a discharge detection portion which detects whether negative ion discharge, indicating discharge in which only negative ions are generated without generating the charged fine water particles, is occurring at the atomizing electrode or not by detecting a discharge current value of a discharge current occurring when the high negative voltage is applied to the atomizing electrode and comparing the discharge current value detected with a predetermined threshold value; and a control portion which carries on reducing the electric field intensity of the electric field generated by the atomizing electrode until the occurrence of the negative ion discharge is no longer detected by the discharge detection portion, if the discharge detection portion detects the occurrence of the negative ion discharge.
 18. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein the control portion is configured to cause the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, the control portion halts the supply of the water to the atomizing electrode by the water supply portion during the period from when the high-voltage power supply circuit is caused to apply the high negative voltage to the atomizing electrode until a predetermined first time has elapsed, and when the first time has elapsed after causing the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, the control portion causes the discharge detection portion to detect whether the negative ion discharge is occurring or not.
 19. The electrostatic atomizing device according to claim 18, wherein, when the occurrence of the negative ion discharge is detected by the discharge detection portion, the control portion further causes the discharge detection portion to detect whether the negative ion discharge is occurring or not during the period from the detection of the occurrence of the negative ion discharge until a predetermined second time has elapsed, and when the occurrence of the negative ion discharge is detected by the discharge detection portion during the period from the time of detection of the occurrence of the negative ion discharge until the second time has elapsed, the control portion reduces the electric field intensity of the electric field generated by the atomizing electrode.
 20. The electrostatic atomizing device according to claim 17, wherein the water supply portion is a Peltier element provided at the base of the atomizing electrode.
 21. The electrostatic atomizing device according to claim 19, wherein the second time is 1 minute.
 22. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein the control portion reduces the electric field intensity of the electric field generated by the atomizing electrode by reducing a voltage value of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit.
 23. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein a plurality of voltage values are set in advance as voltage values of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, and the control portion reduces in steps the voltage value of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, according to the discharge current value detected by the discharge detection portion.
 24. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein the control portion turns OFF and then turns ON the high-voltage power supply circuit as well as reduces the voltage value of the high negative voltage applied to the atomizing electrode.
 25. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein a plurality of voltage values are set in advance as voltage values of the high negative voltage applied to the atomizing electrode by the high-voltage power supply circuit, and the control portion repeatedly turns OFF and then turns ON the high-voltage power supply circuit as well as reduces in steps the voltage value of the high negative voltage applied to the atomizing electrode, until the occurrence of the negative ion discharge is no longer detected by the discharge detection portion.
 26. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein the control portion reduces the voltage value of the high negative voltage applied to the atomizing electrode, and when as a result the occurrence of the negative ion discharge is no longer detected by the discharge detection portion, further reduces the voltage value of the high negative voltage.
 27. The electrostatic atomizing device according to claim 22, further comprising a storage portion which stores the voltage value of the high negative voltage obtained when the discharge detection portion no longer detects the negative ion discharge, wherein the control portion causes the storage portion to store the voltage value of the high negative voltage obtained when the discharge detection portion no longer detects the negative ion discharge, and the control portion sets the voltage value stored in the storage portion as a default voltage value.
 28. The electrostatic atomizing device according to claim 17, further comprising a high-voltage power supply circuit which applies the high negative voltage to the atomizing electrode, wherein the control portion halts the supply of the water to the atomizing electrode by the water supply portion during the period from when the high-voltage power supply circuit is caused to apply the high negative voltage to the atomizing electrode until a predetermined first time has elapsed, and when the first time has elapsed after causing the high-voltage power supply circuit to apply the high negative voltage to the atomizing electrode, the control portion causes the discharge detection portion to detect whether the negative ion discharge is occurring or not, and when the discharge detection portion detects that the negative ion discharge is occurring when the first time has elapsed after the high-voltage power supply circuit is caused to apply the high negative voltage to the atomizing electrode, until the occurrence of the negative ion discharge is no longer detected by the discharge detection portion, the control portion repeats processing of judging the discharge current value detected by the discharge detection portion, and reducing the voltage value applied to the atomizing electrode as the high negative voltage by a first voltage value when a discharge current value detected is less than a predetermined threshold value, otherwise reducing the voltage value applied to the atomizing electrode as the high negative voltage by a second voltage value which is different from the first voltage value when a discharge current value detected is equal to or greater than the predetermined threshold value.
 29. The electrostatic atomizing device according to claim 28, wherein the first voltage value is smaller than the second voltage value.
 30. The electrostatic atomizing device according to claim 17, further comprising an opposing electrode provided opposing the atomizing electrode, wherein the control portion reduces the electric field intensity of the electric field generated from the atomizing electrode toward the opposing electrode by causing the atomizing electrode and the opposing electrode to be moved apart.
 31. The electrostatic atomizing device according to claim 18, wherein the first time is a time in the range from 5 seconds to 30 seconds.
 32. An air conditioner, comprising: an electrostatic atomizing device which includes; an atomizing electrode which generates charged fine water particles negatively charged in the form of mist, by generating an electric field when a high negative voltage is applied thereto in a state in which water is supplied; a water supply portion which supplies the water to the atomizing electrode; a discharge detection portion which detects whether negative ion discharge, indicating discharge in which only negative ions are generated without generating the charged fine water particles, is occurring at the atomizing electrode or not by detecting a discharge current value of a discharge current occurring when the high negative voltage is applied to the atomizing electrode and comparing the discharge current value detected with a predetermined threshold value; and a control portion which carries on reducing the electric field intensity of the electric field generated by the atomizing electrode until the occurrence of the negative ion discharge is no longer detected by the discharge detection portion, if the discharge detection portion detects the occurrence of the negative ion discharge; and an air conditioning portion which performs air conditioning. 